Method and apparatus for intertwisting lengths of filamentary material

ABSTRACT

A method and apparatus for intertwisting lengths of relatively stiff, deformable monofilament or multifilament material to form a stranded segment, such as to form the intertwisted ends or legs of a wire bundle comprising a portion of the bristles of a wire brush. The twisting is accomplished by gripping each length to be twisted at one end in a stationary gripping mechanism and slidably holding the lengths in a rotatable twisting head that locates the respective portions of the lengths that are held thereby in fixed relation to one another and symmetrically spaced about the axis of rotation of the twisting head. The twisting head is initially moved axially to a predetermined axial spacing from the gripping mechanism and when the desired spacing is achieved the twisting head is rotated through a predetermined angle to intertwist the lengths. When the rotation is stopped the steps are then repeated sequentially until the lengths are intertwisted a desired number of helical convolutions.

Dec. 19, 1972 METHODIAND APPARATUS FOR INTERTWISTING LENGTHS OFFILAMENTARY MATERIAL Inventor: Arthur T. Schofield, Brecksville,

Ohio

Assignee: The Manufacturers Brush Company,

Cuyahoga, Ohio Filed: Jan. 28, 1971 Appl. No.: 110,531

[52] U.S. Cl ..l40/149, 300/21 [51] Int. Cl. ..B2lf 7/00 [58] Field ofSearch ..l40/l15, 14 9; 300/2, 21; 15/198, 200, 206

[56] References Cited UNITED STATES PATENTS 1,493,670 5/1924 Galvin..3()0/2l 2,740,148 4/1956 Nelson et al... 300/21 2,742,327 4/1956 Marks..300/2 2,755,496 7/1956 Benyak 300/21 3,304,568 2/1967 Nelson ..300/2lIO C Primary ExaminerLowell A. Larson Attorney-McCoy, Greene & Howell[57] ABSTRACT A method and apparatus for intertwisting lengths ofrelatively stiff, deformable monofilamcnt or multifilament material toform a stranded segment, such as to form the intertwisted ends or legsof a wire bundle comprising a portion of the bristles of a wire brush.The twisting is accomplished by gripping each length to be twisted atone end in a stationary gripping mechanism and slidably holding thelengths in a rotatable twisting head that locates the respectiveportions of the lengths that are held thereby in fixed relation to oneanother and symmetrically spaced about the axis of, rotation of thetwisting head. The twisting head is initially moved axially to apredetermined axial spacing from the gripping mechanism and when thedesired spacing is achieved the twisting head is rotated through apredetermined angle to intertwist the lengths. When the rotation isstopped the steps are then repeated sequentially until the lengths areintertwisted a desired number of helical convolutions 12 Claims, 24Drawing Figures PAIENTED DEC 19 I972 ROTATION (DEGREES) SHEEI 1 [1F 7PRIOR ART o 3 l I (A) l2 I H2 2 2/42/2234 3 6 2 INVENTOR.

TRAVEL (INCHES) FIG. 3

ARTHUR T. SCHOFIELD M0804 8 J/awell ATTORNEYS P'A'TENIEMEM m2 3.706.329

SHEET 2 BF 7 W FIG. 2 I5 5523/ 2? 22 IO .1

INVENTOR. ARTHUR T. SCHOFIELD 440604,, Gaeene 8 Jewell ATTORNEYSP'A'TENTED 05c 19 I972 sum 3 or 7 FIG. 5

(PRIOR ART) ARTHUR T. SCHOFIELD BY M0 am a J/ g ATTORNEYS PATENTEDBEB 19I972 SHEET 5 BF 7 INVENTOR.

ARTHUR T. SCHOFIELD IO BY m Ma 60, Ed/(well ATTORNEYS PA TENTED 19 3.706, 329

sum 5 OF 7 INVENTOR.

ARTHUR T. SCHOFIELD vM0608 0m a /well ATTORNEYS PA TENTED I97? 3. 706.329

SHEET 7 BF 7 I PIILSE BALL NUT lO2 l AMPL'F'ER DRIVE MOTOR I PuLsE i I FAMPLIFIER I PULSE SPINDLE READER I MoToR DRIVE MOTOR PULSE AMPLIFIER II05 I PULSE l PuLsE INDEXING I AMPLIFIER MOTOR MOTOR LIOG J 59 FIG.

56 U- E III 43- Ill I l 4| J FIG. IO

INVENTOR. ARTHUR T. SCHOFIELD BY Ma 60. Gm 8 Jewel! ATTORNEYS BACKGROUNDOF THE INVENTION This invention relates to a method and apparatus forintertwisting lengths of relatively stiff deformable filamentarymaterial and especially to such a method and apparatus as used tointertwist the ends or legs of a wire bundle comprising part of thebristles of a wire brush. More particularly the invention relates toindustrial wire brushes often called knot wheel brushes and to animproved method and machine for their construction.

Conventional knot wheel brushes are formed with a central anchor portionusually a disc with a plurality of apertures spaced around itsperipheral edge, and bundles of wire filaments or bristles that areinserted through the apertures. The bristle bundles are bent in themiddle to form a bight and the ends twisted together helically to formthe so-called knots. The ends of the knots face radially outward andform a generally disc-like brush body with a narrow, generallycylindrical brush face. Conventional machines for producing such brushesare readily available. Typically such machines are provided withautomatic bristle feed mechanisms, such as is shown and described, forexample, in US. Pat. No. 2,742,327.

The operative portion of the twisting mechanism includes a membercommonly called a nose which is generally a frustoconical element with abifurcated end portion having an aligned pair of transverse bristlereceiving apertures located in the bifurcated portion. In the operationof such prior art devices, an anchor plate is mounted in the machine inthe vicinity of the'nose. The nose is then positioned to receive theedge of the anchor plate between the bifurcations of the nose and theplate is indexed to align one ofits apertures with the apertures in thenose. A bristle bundle is then fed into the aligned nose and plateaperture.

In the prior art, twisting has been performed in two stages. In thefirst stage the nose is backed off a short distance to bend or breadkthe bristles and to clear the edge of the plate. In the second stage thenose is backed off the remainder of the length of the bristles whilesimultaneously undergoing rotation about its longitudinal axis. Thus inthe second stage the nose moves helically relative to the anchor plate.It will be appreciated that the helical path of the nose in prior artdevices was continuous, being typically generated by a system in whichthe rotational movement of the nose was synchronized with and directlyproportional to its longitudinal movement. The longitudinal movement ofthe nose was controlled by a cam actuated system.

In machines of the prior art when the wound bristles were released fromthe nose they would recoil or unwind slightly. The degree to whichrecoil occurred was a limiting factor as to the degree of tightness withwhich the knot could be wound. A tight knot is generally desirableinasmuch as the bristles tend to support one another and prevent longbristle fracture-a significant source of brush wear.

Another problem inherent in prior art devices is that the cams whichcontrolled the rotary and axial movement of the nose would wear out atfrequent intervals thus requiring shutdown of equipment for repair. Alsosincedifferent cams would be required for different brushes the camswould have to be changed and adjusted before each production run, all ofwhich is burdensome and time-consuming.

The methodand apparatus of the present invention, however, resolve thedifficulties indicated above and afford other features and advantagesheretofore not obtainable.

SUMMARY OF THE INVENTION It is among the objects of the invention toprovide an improved method and apparatus for controlling automatically,compound movements of a twisting head or nose used to intertwist aplurality of lengths of relatively stiff deformable filamentary materialsuch as wire bundles. 7

Another object is to facilitate remote adjustment of the compoundmovements of a twisting mechanismv used to intertwistthe end portions ofwire bundles in making knot wheel brushes.

Still another object is to assure accuracy and uniformity duringrepeated cycling of a machine for intertwisting the end portions of wirefilaments to secure the bristles of knot wheel brushes.

A further object is to achieve improved intertwisting of the endportions of wire bundles used in making knot wheels and to therebyproduce a brush with improved life and reduced bristle fracture in theends of the brush bristles.

A still further object is to produce a knot wheel brush capable ofhandling more rigorous service conditions and having a longer servicelife than has heretofore been obtainable.

Another object is to provide an apparatus for intertwisting the endportions of wire bundles which apparatus is readily adaptable tonumerical control.

These and other objects are accomplished by the method and apparatus ofthe present invention which, in a broad sense, has application to theintertwisting of a plurality of lengths of any relatively stiffdeformable filamentary material.

The method comprises anchoring an end portion of each length of materialto fix the respective end portions relative to one another. It will benoted that in the apparatus shown, the anchoring step is accomplished bylooping a double-length bundle of filamentary material through anapertured anchor plate, although other anchoring means may be employedwith either single or double length bundles of filamentary materials,all as will be apparent to persons of ordinary skill.

At the same time the anchored lengths are slidably held intermediate therespective anchored end portions and the free ends thereof, in arotatable twisting head that locates the portions of the lengths held bythe twisting head in fixed relation to one another and symmetricallyspaced about the axis of rotation of the twisting head. With the lengthsheld in this condition the twisting head is initially moved axially awayfrom the anchored ends a predetermined distance while the lengths slidetherethrough. After the axial movement is stopped the twisting head isrotated through a predetermined angle to intertwist the lengths in theirrespective spans between the anchored ends and the twisting head.

It is preferred that the axial movement be so con trolled during thisrotation that there is a relatively small axial retraction away from thegripping mechanism. Accordingly an additional portion of each length ofmaterial with slide forwardly through the twisting mechanism to supplythe additional material required due to the helical form taken by theintertwisted lengths. The above two steps are then repeated until thelengths have been intertwisted a predetermined number of turns. Theinvention thus defined produces in the case of knot wheel brushes, animproved knot formation.

According to one particular aspect of the invention the twisting iscontrolled so as to produce a variable lead or pitch in the intertwistedportions, preferably a progressively increasing lead or pitch so as toreduce fanning of the bristles at the end of a knot wheel brush and toreduce the tendency of ofintertwisted lengths to unwind slightly whenreleased from the twisting head.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view fromabove showing a knot wheel plate adapted to receive a bundle of wirebristles for forming a knot wheel brush, and a twisting head forintertwisting the legs of the bundle;

FIGS. 2A through 2N comprise a group of fragmentary vertical elevationsillustrating sequentially the various steps in the intertwisting of thelegs ofa wire bundle to form one segment of the bristles of a knot wheelbrush;

FIG. 3 is a chart illustrating graphically a plot of sequential stepstaken by the twisting head according to the procedure illustrated inFIG. 2;

FIG. 4 illustrates a knot wheel brush constructed according to themethod and apparatus of the present invention;

FIG. 5 illustrates a knot wheel brush constructed according to prior artpractices;

. FIG. 6 is a plan view of a machine for twisting wire bundles to formknot wheels;

FIG. 7 is a fragmentary elevation of the machine of FIG. 6;

FIG. 8 is a fragmentary horizontal section on an enlarged scale takenthrough the machine of FIGS. 6 and FIG. 9 is a fragmentary sectionalview taken on the line 9-9 of FIG. 8;

FIG. 10 is a fragmentary sectional view taken on the line 10-10 of FIG.8; and

FIG. 11 is a basic function block; schematic and fragmentarydiagrammatic representation of the control system for the machine ofFIGS. 6 to 10.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring more particularly tothe drawings and initially to FIG. 1 there is shown a knot wheel plate10 mounted on an indexing head 11. The plate 10 has a number ofperipheral holes 14 of oblong form symmetrically spaced about the outermargin thereof and each hole 14 is adapted to receive two or morebundles 15 of wire filaments or bristles. The bundles 15 are secured tothe knot wheel plate 10 by forming a knot with a twisting head inaccordance with the method of the invention. The twisting head 20 has athreaded shank 21 that is threaded into the end of a spindle 22, and atapered forward end 23 with a transverse slot 24 cut therethrough-toform bifurcations adapted to receive the knot wheel plate 10therebetween.

Extending through each of the bifurcations in the tapered forward end 23perpendicular to the slot 24 is a transverse opening 25. The openings 25are somewhat funnel shaped and flared outwardly and rearwardly towardthe conical surface of the tapered forward end 23.

FIG. 2 illustrates sequentially the operation of the twisting head 20 informing the knot to secure the bun dles 15 to the knot wheel plate 10and also to form the wire bundles so as to position the ends of thebristles correctly and properly in forming a part of the bristles of awire brush.

Views illustrating the various sequential steps in the operation of thetwisting head 20 are identified by the letters A through N in FIG. 2 andit will be seen that at the outset, the twisting head 20 has been movedforwardly toward the knot wheel plate 10 from its position illustratedin FIG. 1 so that the tapered forward end 23 is positioned over theouter margin of the plate 10 with the outer margin received in the slot24 and with the transverse openings 25 in the tapered forward end 23aligned with one of the peripheral holes 14 in the knot wheel plate 10.One of the wire bundles 15 has been inserted through the respectivealigned openings 25 and a peripheral hole 14, so that end portions orlegs of approximately equal length (such legs being referred to aslengthsherein) extend outward on opposite sides of the knot wheel plate10.

At view B the twisting head 20 has been retracted in an axial directionaway from the knot wheel plate 10 a distance of 13/16 inch so as to bendthe bundle 15 to form a bight and also so that the bifurcations of thetwisting head 20 have cleared the edge of the plate.

At view C the twisting head 20 after having f rst been axiallyretracted, has been rotated in the direction shown while continuing aslight axial retraction to overlay the legs of the wire bundle 15 andstart the formation of a knot.

At view D the twisting head has been retracted axially an additionalaxial increment without additional rotation so that the total axialretraction is 1 1/64 inches.

At view E the twisting head has been rotated an additional 180 whilecontinuing a small axial retraction so that a full 360 intertwisting ofthe legs has been accomplished.

At view F the twisting head has been retracted axially an additionalaxial increment so that the total axial retraction has been 1 15/64inches.

At view G the twisting head has been rotated an angle of 180 whilecontinuing a small axial retraction so that the total twistingaccomplished has been 1% turns or 540.

Views H through M illustrate the remaining steps taken to complete thesequential intertwisting of the legs of the bundle 15.

At view N the twistinghead 20 has been retracted past the ends of thebristles to free the bundle 15 from the twisting head 20 and completethe formation of the knot.

These steps are illustrated graphically in FIG. 3. The sequentialtwisting thus described produces improved knots which reduce theoccurrence and extent of long bristle fracture and afford increasedbristle wear and effectiveness. In the preferred embodiment of themethod of the invention the sequential steps are so performed as toprovide a progressively increasing lead for the intertwisted bristlelegs so that the knot is tightest adjacent the knot wheel plate 10.Because of the progressively increasing lead the knot has less tendencyto unwind when the bristle ends are released from the twisting head 20.

The improved bristle end form is illustrated in FIG. 4 which shows aknot wheel brush A formed according to the method of the invention. Thebrush A has bristle bundles l5 bent to form a bight 30 and with theresulting legs intertwisted to form a knot 31. The twisted legs have agenerally helical form in the knot and the helices have a progressivelyincreasing lead from the edge of the plate toward their outer ends. Theouter ends have a relatively uniform radial extension because the knothas not experienced any substantial unwinding after the legs wereintertwisted.

FIG. 5 illustrates a prior art knot wheel brush B wherein the bristleends of each leg of the respective wire bundles fan outwardly to agreater degree than in brushes constructed according to the presentinvention. (The relative amount of fanning is exaggerated for purposesof illustration). This is caused by the partial unwinding of thebristles after twisting to form a knot. This, in turn, is caused by thefact that the knot helices of the prior art brush B have a generallyuniform lead.

FIGS. 6 through 10 illustrate a machine embodying the present inventionfor forming knot wheel brushes of the .type shown in FIG. 4 and which isespecially adapted for the practice of the method of the presentinvention. The machine comprises an indexing assembly C adapted toposition and index a knot wheel plate 10, and a twisting head driveassembly D adapted to provide the axial and rotary drive for thetwisting head 20.

The indexing assembly C is mounted for horizontal adjustment in adirection-perpendicular to the indexing head 11 on a main frame 40 thatsupports a pair of vertically spaced horizontal guide rods 41. Acarriage 42 is slidably mounted for horizontal travel on the rods 41 soas to provide for proper lateral positioning of a knot wheel plate 10carried on the indexing head 11. The adjustment is accomplished by meansof an adjusting screw 43 which is joumaled in the main frame 40 andwhich drives an adjusting nut 44 secured to the carriage 42.

The indexing head 11 is of compound construction and includes a centershaft 45 (FIG. 8) having a forward end that receives a knot wheel plate10, and an annular groove in its forward end that receives a lock ring46 to secure a knot wheel plate 10 on the head.

The center shaft 45 is received within a pair of axially alignedbushings including a forward bushing 47 and a rear bushing 48, thebushings being threadedly secured to one another to form a single unit.The bushings 47 and 48 are in turn received in a bearing sleeve 49 thatis joumaled in a bearing unit 50. The bearing sleeve 49 has a conicaltaper at its forward end that is adapted to receive a correspondingconically tapered part of the forward bushing 47 to provide a taper lockwhen the bushings 47, 48 and sleeve 49 are assembled.

The center shaft 45 has a threaded rearward end that receives a lockingnut 52 with a control wheel 53 secured thereto. The nut 52 bears againstthe rearward end of the bearing sleeve 49 so that by tightening down thenut 52 against the bearing sleeve 49 the lock ring 46 firmly clamps aknot wheel plate 10 in place against the front face of the forwardbushing 47.

A drive gear 54 secured to the rearward end of the bearing sleeve 49(FIGS. 7 and 8), meshes with another gear 55 mounted on a shaft 56joumaled in the carriage 42. The shaft 56 also carries a helical gear 57that meshes with another helical gear 58 on the output shaft of anelectro-hydraulic stepping motor 59 which may be for example of the typesold commercially under the trade designation FANUC Pulse Motor No. 56555. The control system for the stepping motor 59 can thus be used todrive the motor through a predetermined angular distance to index a knotwheel plate 10 through the angle necessary to properly position theplate to a new bundle receiving position after completion of eachtwisting operation.

The twisting head drive assembly D comprises a frame 60 that supports aforward bearing unit 61 in which the spindle 22 is slidably joumaled.The spindle 22 has a splined rearward end length 62 with a sleeve 63with matching internal splines slidably received thereon, the sleeve 63being joumaled in a rear bearing unit 64 also supported on the frame 60.The sleeve 63 has a pinion 65 secured thereto by a lock nut 66. Thepinion 65 is driven by the output gear 67 of an electrohydraulicstepping motor 69 that serves to turn the spindle 22 through anaccurately controlled predetermined angular distance in response tocontrol pulses fed to the stepping motor 69 by a control system to bedescribed below.

The controlled axial movement of the twisting head 20 during itstwisting operation in accordance with the present invention isaccomplished by means of a ball nut assembly 70 best illustrated inFIGS. 8 and 9. The ball nut assembly 70 cooperates with the spindle 22which has a helical groove 71 formed in a portion of its cylindricalsurface to provide a race for steel drive balls 72. The balls 72 areseated in hemispherical seats within a ball nut 73 so that rotation ofthe ball nut 73 when the spindle is held against free rotation by theengagement of the pinion 65 with the gear 67, causes axial movement ofthe spindle 22 unless the pinion 65 is driven at the same rotationalspeed as the ball nut 73. With this arrangement both axial androtational movement of the spindle 22 can be accomplished at the sametime.

The ball nut assembly 70 has a housing 74 that is slidably supported atits ends on horizontal guide rods 75 and 76 mounted in brackets 77 and78 on the frame 60. A keyed shaft 80 slidably extending through the ballnut housing 74 is joumaled in the brackets 77 and 78 between the rods 75and 76. A pinion 81 is keyed to the shaft 80 and is free to slideaxially along the shaft 80 with the ball nut housing 73. The pinion 8 1has a hear ing sleeve 82 joumaled in the ball nut housing 73, and mesheswith a ball nut gear 84 that also has a bearing sleeve 85 joumaled inthe ball nut housing 74. The

bearing sleeve 85 is threaded onto the ball nut 73 so that the nutisturned by the gear 84. The shaft 80 extends through the bracket 78 andhas a pinion 87 mounted on its rearwardly extending end. The pinion 87meshes with the output gear 88 of an electrohydraulic stepping motor 89.Both of the electrohydraulic stepping motors 69 and 89 may be, forexample, of the type commercially available under the trade designationFANUC Pulse Motor No. 3-555.

Secured to the bottom of the ball nut housing 74 is a rack 91 that isengaged by a pinion 92 mounted on a shaft 93 journaled in bearing blocks94 and 95 on the frame 60 (FIG. 9). A shaft gear 96 mounted on left handend of the shaft 93 as viewed in FIG. 9, meshes with the output gear 97of a drive motor 98. The motor 98 is used only to adjust the position ofthe twisting head 20 before and after the twisting operation of the head20 is performed. It is not used during the twisting operation. The motor98 may be, for example, a three phase plugging reversing electric motorcommercially available from Louis Allis Chalmers Corporation. This typeof motor will make one revolution and reverse one revolution and thenplug to a stop for one half second.

OPERATION The construction of a knot wheel brush such as the brush A ofFIG. 4, using the machine of FIGS. 6 to 10, in accordance with themethod of the invention begins by mounting a knot wheel plate 10 on theindexing head 11. This is accomplished merely by placing the plate onthe center shaft 45 with one face against the end face of the forwardbushing 47, and then inserting the lock ring 46 in the annular slot onthe center shaft 45. The wheel 53 is then turned to tighten the lockring 46 against the plate 10 so that the plate is tightly held betweenthe lock ring 46 and the forward bushing 47.

The apertures 14 in the knot wheel plate 10 are positioned in apredetermined initial angular position using a locating device forexample that has been made for the specific size and form of the plate.The motor 98 is then operated to move the carriage 70 along with thespindle 22 and twisting head until the bifurcations of the twisting head20 receive the knot wheel plate 10 therebetween with the transverseholes of the twisting head 20' aligned with an aperture 14 in the knotwheel plate 10. The motor 98 is stopped when the desired position hasbeen reached and is not normally operated again until the constructionof a brush has been completed.

It will be noted that before the positioning of the twisting head 20 tothe position shown in FIGS. 6 through 9 (as well as in FIG. 2 (A)), thespindle is moved by the ball nut assembly 70 to its maximum forwardextension relative to the assembly 70. This is accomplished by operatingthe electro-hydraulic stepping motor as viewed in FIG. 9 until thespindle 22 has moved relative to the nut 73 to approximately theposition illustrated in FIG. 8.

With the holes 25 in the twisting head 20 thus aligned with an aperture14 in the knot wheel plate 10, a bundle of wire bristles 15 is insertedhorizontally through the respective holes 25 and aperture 14 asillustrated in FIG. 2 (A). The feeding of the wire bundles may beaccomplished using precut cartridge loaded filaments or in any otherfashion as will be apparent to persons of ordinary skill.

To begin the forming of the wire bundle 15 the electrohydraulic steppingmotor 89 is operated to turn the ball nut 73 in a clockwise direction asviewed in FIG. 9 to retract the spindle 22 and twisting head 20 apredetermined axial distance. The resulting bight formed in the wirebundle is illustrated in FIG. 2 (B).

After the twisting head 20 has been retracted the predetermined axialdistance so that the bifurcations clear the edge of the plate 10, theelectro-hydraulic stepping motor 69 is operated together with the motor89 to turn the spindle 22 through a predetermined angle which in theoperation illustrated is 180, and at a rotational speed just slightlyless than the speed of the ball nut 73 so that the axial movement of thespindle will be substantially reduced during the twisting movement.According to the preferred embodiment it is desired that some axialretraction be continued during the turning of the spindle 22 andtwisting of the respective wire bundle 15 so that rotational speed ofthe spindle 22 in response to the drive from the motor 69 is geared insuch a way as to be slightly slower than the speed of the ball nut 73.The speed differential will result in some axial retraction but at areduced rate as compared with the initial rate of spindle retraction.The speed of the two stepping motors 69 and 89 however, is preferablyexactly the same. The procedure is then repeated with theelectro-hydraulic stepping motor 89 being operated continuously and theelectro-hydraulic motor 69 being operated intermittently to provide thealternating axial movement and rotary or turning movement of the spindleaccompanied by a small axial retraction but at a reduced rate.

It will be noted that during this portion of the knot wheel constructionprocedure the housing 74 remains stationary relative to the horizontalguide rods 75 and 76. The total axial travel of the twisting head 20 inthe operation illustrated is 3% inches while the total angular movementis 180. After the desired twisting has been accomplished the retractionis continued until the bristle ends have passed entirely through theholes 25 in the twisting head 20 after which the electro-hydraulicstepping motors 69 and 89 are operated to turn the twisting head 20another 90 so that it is at a new starting position relative to theplate 10.

The knot wheel plate 10 is then indexed to a new angular position .usingthe electro-hydraulic stepping motor 59 while at the same time, theelectro-hydraulic stepping motor 89 is operated in a reverse directionto move the twisting head 20 forward again to its maximum forwardextension and with its transverse holes 25 aligned with an aperture 14for starting a new twisting operation. A new bundle 15 is then insertedin the manner described above and the twisting operation re peated untilthe desired number of bundles 15 have been secured to the knot wheelplate 10. The knot wheel plate 10 is then removed from the indexing head11 and a new plate mounted in position.

CONTROL SYSTEM FIG. 11 shows in diagrammatic form a numerical controlsystem for the machine of FIGS. 6 through 10. The system controls theoperation of the electrohydraulic stepping motors 59, 69 and 89 through,for example, the illustrative series of operational steps describedabove and illustrated in FIGS. 2 and 3. The system uses informationstorage means such as a I060ll 0481 punched tape containing controlinformation for making a specific knot wheel brush. The tape is normallyadvanced continuously through a tape reader 101 that may use for examplea light beam detector to complete intermittently a signal producingcircuit. In the embodiment shown, four parallel channels ofinformationare punched into the tape.

The resulting signals for each channel in the form of electrical pulsesare fed to a motor control unit 102 which may be for example, the unitcommercially available under the trade designation ICON 410 from ICORCorporation of 156 6th Street, Cambridge, Massachusetts. The controlunit 102 includes four pulse amplifiers 103, 104, 105 and 106 which areadapted to amplify the signal pulses from the tape reader 101 to produceelectrical driving pulses of the proper voltage and amperage for drivingthe respective stepping motors.

As to the ind exing stepping motor 59 it is desirable that the amount ofshaft rotation for each driving pulse from the respective pulseamplifier 106 be small enough that a difference of one indexing pulseaffords an extremely small increase or decrease in the angular movementof the indexing head 11 during the indexing cycle. This capacity forvernier adjustment of the angular indexing movement is necessary inorder to accommodate knot wheel plates of different size and differentnumber of peripheral apertures. Accordingly the number of pulsesrequired to turn the indexing head 11 through one full 360 turn shouldbe fairly large and is preferably divisible by as many integers aspossible.

It will be noted that the gears 54, 55, 57 and 58 provide a reduction of16 between the shaft of the motor 59 and the indexing head 11 so thatthe motor 59 will turn through three times the angle that the indexinghead 11 will turn through in response to each driving pulse. Accordinglyif 50 pulses are required to rotate the stepping motor 59 through onefull turn (i.e., 7.2 of rotation per pulse) then 150 pulses will turnthe indexing head through one full 360 turn (i.e., 2.4 of rotation perpulse). Thus the angular movement of the indexing head may be easilyadjusted to provide for knot wheel plates having for example 10, 15,25or knots. For example if a plate is to have 25 circumferentially spacedknots then the number of pulses punched into the tape for one indexingcycle would be 150 divided by 25 or six pulses.

The spindle stepping motor 69 and ball nut stepping motor 89 arepreferably rotated through equal angles in response to each pulse fromtheir respective pulse amplifiers 103 and 105. This greatly simplifiesthe preparation of control punch tapes. As to the spindle stepping motor69, 300 pulses are required to turn the motor through one full'3 60turn. Since the gear 65 will turn through twice the angle of the gear 67in response to one pulse, the spindle 22 will require 150 pulses for onefull 360 turn. Thus if the spindle turns through 810 (i.e., 2 /4 turns)during the twisting operation this will require a total of 338 pulses.

The ball nut motor 89 also requires 300 pulses for one full 360 turn andsince the ball nut 73 will be turned through slightly more than twicethe angle thatthe motor 89 will be turned by one pulse, less than 150pulses are required to turn the ball nut one full turn. The pitch of thehelices 71 in the spindle is such that one full revolution of the ballnut will move the spindle in an axial direction 1% inches.

Since the ball nut 73 must move the spindle both backward and forward itis necessary that the control pulses for reversing the ball nut (i.e.,extending the spindle) be provided on a separate channel to a separatepulse amplifier 104 and that the respective driving pulses be deliveredto the reversing terminal of the ball nut motor 89.

It will be seen that if an equal number of pulses are fed to the motors69 and 89 simultaneously, the ball nut 73 will turn in the samedirection and at a slightly faster rate than the spindle 22 so that asmall axial movement will result. The gears 87 and 88 provide the smallspeed differential between the ball nut 73 and the spindle 22 inresponse to an equal number of pulses fed at the same rate, in order tocontinue some retraction movement of the spindle during its rotation.This speed differential may be increased by increasing the number ofteeth on the gear 88 or reducing the number of teeth on the gear 87 sothat even though the motors 69 and 89 operate at the same speed the ballnut will turn slightly faster than the spindle 22 and thus provide thesmall axial retraction of the spindle 22 during rotation.

It will be noted that during those steps of the operation wherein apurely axial movement of the spindle is required, only the motor 89 willbe suppliedwith driving pulses. These pulses are supplied continuouslyat the same rate through the twisting operation. During those stepswhere rotation is desired, a group of driving pulses are fed(corresponding to the angular movement desired) to the stepping motor69.

Table l below represents the control information, i.e., the number ofpulses punched in each of the four parallel channels in a punched tapein order to control the machine during the sequences illustrated inFIGS. 2 and 3. In this instance the pulses are fed at a rate of 2,000pulses per second and since a total of 815 pulses are required during acomplete twisting and indexing cycle the total time required will be 0.4seconds. However, after completion of the twisting and the subsequentindexing of the knot wheel plate 10 to a new angular position it isdesirable to have a delay of at least 9% second for inserting a newbristle bundle into the twisting head 20 and the respective apertures inthe knot wheel plate 10. Accordingly, the total time required forknotting each bundle would be about 0.9 seconds. Thus a plate with 18knots would require 16 seconds to manufacture (i.e., 225 brushes perhour).

While the method and machine of the invention have been shown anddescribed with respect to specific embodiments thereof this is intendedfor the purpose of illustration rather than limitation and other embodiments and modifications will be apparent to those skilled in the artupon a reading of the specification. Accordingly, the patent is not tobe limited in any manner that is inconsistent with the extent to whichthe progress in the art has been advanced by the invention.

1 claim:

1. A method for intertwisting a plurality of lengths of relativelystiff, deformable filamentary material .comprising the steps of:

anchoring an end portion of each length to fix the respective endportions relative to one another;

l060l l 0482 slidably holding the lengths intermediate the respectiveanchored end portions and the free ends thereof in a rotatable twistingelement that locates the slidably held portions of the lengths in fixedrelation to one another and symmetrically spaced about the axis ofrotation of said twisting element;

moving said twisting element axially away from said anchored endportions and linearly along said lengths a predetermined distance;

thereafter rotating said twisting element through a predetermined angleto intertwist said lengths in their respective spans between saidanchored end portions and said twisting element, and

repeating the two steps next above until said lengths are intertwisted apredetermined number of turns.

2. A method as defined in claim 1 wherein the predetermined anglethrough which said twisting element is rotated becomes progressivelysmaller relative to the next preceding axial movement of said twistinghead, with each successive rotating step.

3. A method for intertwisting a plurality of lengths of relativelystiff, deformable filamentary material comprising the steps of:

anchoring an end portion of each length with a stationary anchoringelement to fix the respective end portions relative to one another;slidably holding the lengths intermediate the respective anchored endportions and the free ends thereof in a rotatable twisting element thatlocates the slidably held portions of the lengths in fixed relation toone another and symmetrically spaced about the axis of rotation of saidtwisting element;

moving said twisting element axially away from said anchoring elementand linearly along said lengths a predetermined distance;

thereafter rotating said twisting element through a predetermined angleto intertwist said lengths in their respective spans between saidanchoring element and said twisting element; repeating the two stepsnext above until said lengths are intertwisted a predetermined number ofturns; moving said twisting element axially away from said anchoringelement an additionsl axial distance until the free ends of said lengthsare released from said twisting element; rotating said twisting elementthrough an additional angular increment to a predetermined startingattitude, and

moving said twisting element axially toward said anchoring element to anew starting position.

4. A method for intertwisting a plurality of lengths of relativelystiff, deformable filamentary material comprising the steps of:

anchoring an end portion of each length with a stationary anchoringelement to fix the respective end portions relative to one another;

slidably holding the lengths intermediate the respective anchored endportions and the free ends thereof in a rotatable twisting element thatlocates the slidably held portions of the lengths in fixed relation toone another and symmetrically spaced about the axis of rotation of saidtwisting element; generating a group of electrical driving pulses;moving said twisting element axially away from said anchoring elementand linearly along said lengths a predetermined distance in response toeach of said pulses so that the total distance moved is determined bythe number of said pulses in said group;

thereafter generating a second group of electrical driving pulses;

rotating said twisting element through a predetermined angular incrementin response to each of said pulses of said second group so that thecumulative angle through which said twisting element is rotated isdetermined by the number of pulses in said second group;

repeating the four steps next above until said lengths are intertwisteda predetermined number of turns.

5. The method of constructing a rotary knot wheel brush which includes aknot wheel plate having a plurality of apertures spaced about itsperiphery and a plurality of bristle knots each consisting of anelongated bundle of bristle material bent intermediate its ends to formtwo leg portions which are helically intertwisted, and a bight portionwhich loops through one of said apertures, in a machine having atwisting element with a central axis and a bifurcated end portion havingopposed openings in its furcations transverse to said axis, saidtwisting element being mounted for linear move ment along said axisbetween an extended position and a retracted position and for'rotationabout said axis, means mounting said knot wheel plate with itsperipheral edge located between said furcations when said twistingelement is in said rest position, and for rotary indexing movementbetween a plurality of discrete bristle receiving positionscharacterized by alignment of one of said plate apertures will saidopenings in said twisting element comprising the steps of:

feeding an elongated bristle bundle endwise through one of said plateapertures and aligned openings in said twisting element; generating agroup of driving pulses; moving said twisting element axially away fromsaid plate a predetermined distance along said nose axis in response toeach of said pulses to bend said bundle to form a bight and thenalternately; generating a second group of driving pulses; rotating saidtwisting element about said axis a predetermined angular distance inresponse to each of the pulses of said second group, and

thereafter repeating in alternating relation said axial and rotarymovement of said twisting head until said bundle is intertwisted apredetermined number of turns to form a knot.

6. A method as defined in claim 5 including the additional steps ofgenerating another group of driving pulses representative of the desiredangular indexing movement for rotating said plate to the location of thenext adjacent knot and rotating said plate in response to said othergroup of pulses.

7. A method as defined in claim 6 including the additional steps ofgenerating still another group of driving pulses representative of theaxial movement of said twisting headnecessary to return said head fromits retracted position following the completion of said twisting to itsextended position and moving said twisting head forward in response tosaid pulses of said group.

l060ll 0483 8. In a machine for intertwisting a plurality of lengths ofrelatively stiff, deformable filamentary material and including meansfor anchoring an end portion of each length to fix the respective endportions relative to one another-and a rotatable twisting element forslidably holding the lengths intermediate the respective end portionsand the free ends thereof and for locating the slidably held portions ofthe lengths in fixed relation to one another and symmetrically spacedabout the axis of rotation of the twisting element, the improvementwhich comprises:

means for moving said twisting element axially away from said anchoredend portions at spaced time intervals in progressive increments ofpredetermined axial length while said twisting element is held againstrotation, and

means for rotating said twisting element through angular increments ofpredetermined angular size in alternating relation with said axialincrements, each increment occurring between two sequential steps of theaxial movement thereof, whereby said lengths are intertwistedprogressively along a length span thereof by the alternating turningmovement of said twisting element.

9. A machine as defined in claim 6 wherein said means for moving saidtwisting element axially comprises a stepping motor operativelyconnected to said twisting element for moving said twisting elementaxially in response to stepped rotation thereof and a programmed sourceof driving pulses to turn said stepping motor through a predeterminedangle in response to each pulse.

10. A machine as defined in claim 6 wherein said means for rotating saidtwisting head comprises a stepping motor operatively connected to saidtwisting head and a programmed source of driving pulse to turn saidstepping motor through a predetermined angle in response to each pulse.

11. In a machine for making rotary wire knot wheel brushes and includingan indexing head for holding an apertured knot wheel plate and means forindexing the head through a discrete angle about its axis, a spindlemeans mounting said spindle for rotation and for linear movement alongits axis of rotation, a twisting head carried by said spindle and meansfor feeding bundles of wire bristles laterally through the twisting headand through an aperture in said knot wheel plate, the improvement whichcomprises:

a first stepping motor operatively connected to said spindle for movingsaid spindle axially between an extended bundle receiving position and aretracted position;

a second stepping motor operatively connected to said spindle forrotating said spindle, and

a programmed source of driving pulses for said respective steppingmotors for alternating moving said spindle axially in stepped incrementsand for rotating said spindle between said axial movement to twist saidwire bundle to form a knot securing said bundle to said knot wheelplate.

12. A machine as defined in claim 11 including a third stepping motorfor indexing said knot wheel plate and wherein said programmed source ofelectrical driving pulses includes means for generating groups of pulsesrepresentative of the desired angular indexin movement for said knotwheel plate to operate sai third stepping motor.

l060ll 0484

1. A method for intertwisting a plurality of lengths of relativelystiff, deformable filamentary material comprising the steps of:anchoring an end portion of each length to fix the respective endportions relative to one another; slidably holding the lengthsintermediate the respective anchored end portions and the free endsthereof in a rotatable twisting element that locates the slidably heldportions of the lengths in fixed relation to one another andsymmetrically spaced about the axis of rotation of said twistingelement; moving said twisting element axially away from said anchoredend portions and linearly along said lengths a predetermined distance;thereafter rotating said twisting element through a predetermined angleto intertwist said lengths in their respective spans between saidanchored end portions and said twisting element, and repeating the twosteps next above until said lengths are intertwisted a predeterminednumber of turns.
 2. A method as defined in claim 1 wherein thepredetermined angle through which said twisting element is rotatedbecomes progressively smaller relative to the next preceding axialmovement of said twisting head, with each successive rotating step.
 3. Amethod for intertwisting a plurality of lengths of relatively stiff,deformable filamentary material comprising the steps of: anchoring anend portion of each length with a stationary anchoring element to fixthe respective end portions relative to one another; slidably holdingthe lengths intermediate the respective anchored end portions and thefree ends thereof in a rotatable twisting element that locates theslidably held portions of the lengths in fixed relation to one anotherand symmetrically spaced about the axis of rotation of said twistingelement; moving said twisting element axially away from said anchoringelement and linearly along said lengths a predetermined distance;thereafter rotating said twisting element through a predetermined angleto intertwist said lengths in their respective spans between saidanchoring element and said twisting element; repeating the two stepsnext above until said lengths are intertwisted a predetermined number ofturns; moving said twisting element axially away from said anchoringelement an additionsl axial distance until the free ends of said lengthsare released from said twisting element; rotating said twisting elementthrough an additional angular increment to a predetermined startingattitude, and moving said twisting element axially toward said anchoringelement to a new starting position.
 4. A method for intertwisting aplurality of lengths of relatively stiff, deformable filamentarymaterial comprising the steps of: anchoring an end portion of eachlength with a stationary anchoring element to fix the respective endportions relative to one another; slidably holding the lengthsintermediate the respective anchored end portions and the free endsthereof in a rotatable twisting element that locates the slidably heldportions of the lengths in fixed relation to one another andsymmetrically spaced about the axis of rotation of said twistingelement; generating a group of electrical driving pulses; moving saidtwisting element axially away from said anchoring element and linearlyalong said lengths a predetermined distance in response to each of saidpulses so that the total distance moved is determined by the number ofsaid pulses in said group; thereafter generating a second group ofelectrical driving pulses; rotating said twisting element through apredetermined angular increment in response to each of said pulses ofsaid second group so that the cumulative angle through which saidtwisting element is rotated is determined by the number of pulses insaid second group; repeating the four steps next above until saidlengths are intertwisted a predetermined number of turns.
 5. The methodof constructing a rotary knot wheel brush which includes a knot wheelplate having a plurality of apertures spaced about its periphery and aplurality of bristle knots each consisting of an elongated bundle ofbristle material bent intermediate its ends to form two leg portionswhich are helically intertwisted, and a bight portion which loopsthrough one of said apertures, in a machine having a twisting elementwith a central axis and a bifurcated end portion having opposed openingsin its furcations transverse to said axis, said twisting element beingmounted for linear movement along said axis between an extended positionand a retracted position and for rotation about said axis, meansmounting said knot wheel plate with its peripheral edge located betweensaid furcations when said twisting element is in said rest position, andfor rotary indexing movement between a plurality of discrete bristlereceiving positions characterized by alignment of one of said plateapertures will said openings in said twisting element comprising thesteps of: feeding an elongated bristle bundle endwise through one ofsaid plate apertures and aligned openings in said twisting element;generating a group of driving pulses; moving said twisting elementaxially away from said plate a predetermined distance along said noseaxis in response to each of said pulses to bend said bundle to form abight and then alternately; generating a second group of driving pulses;rotating said tWisting element about said axis a predetermined angulardistance in response to each of the pulses of said second group, andthereafter repeating in alternating relation said axial and rotarymovement of said twisting head until said bundle is intertwisted apredetermined number of turns to form a knot.
 6. A method as defined inclaim 5 including the additional steps of generating another group ofdriving pulses representative of the desired angular indexing movementfor rotating said plate to the location of the next adjacent knot androtating said plate in response to said other group of pulses.
 7. Amethod as defined in claim 6 including the additional steps ofgenerating still another group of driving pulses representative of theaxial movement of said twisting head necessary to return said head fromits retracted position following the completion of said twisting to itsextended position and moving said twisting head forward in response tosaid pulses of said group.
 8. In a machine for intertwisting a pluralityof lengths of relatively stiff, deformable filamentary material andincluding means for anchoring an end portion of each length to fix therespective end portions relative to one another and a rotatable twistingelement for slidably holding the lengths intermediate the respective endportions and the free ends thereof and for locating the slidably heldportions of the lengths in fixed relation to one another andsymmetrically spaced about the axis of rotation of the twisting element,the improvement which comprises: means for moving said twisting elementaxially away from said anchored end portions at spaced time intervals inprogressive increments of predetermined axial length while said twistingelement is held against rotation, and means for rotating said twistingelement through angular increments of predetermined angular size inalternating relation with said axial increments, each incrementoccurring between two sequential steps of the axial movement thereof,whereby said lengths are intertwisted progressively along a length spanthereof by the alternating turning movement of said twisting element. 9.A machine as defined in claim 6 wherein said means for moving saidtwisting element axially comprises a stepping motor operativelyconnected to said twisting element for moving said twisting elementaxially in response to stepped rotation thereof and a programmed sourceof driving pulses to turn said stepping motor through a predeterminedangle in response to each pulse.
 10. A machine as defined in claim 6wherein said means for rotating said twisting head comprises a steppingmotor operatively connected to said twisting head and a programmedsource of driving pulse to turn said stepping motor through apredetermined angle in response to each pulse.
 11. In a machine formaking rotary wire knot wheel brushes and including an indexing head forholding an apertured knot wheel plate and means for indexing the headthrough a discrete angle about its axis, a spindle means mounting saidspindle for rotation and for linear movement along its axis of rotation,a twisting head carried by said spindle and means for feeding bundles ofwire bristles laterally through the twisting head and through anaperture in said knot wheel plate, the improvement which comprises: afirst stepping motor operatively connected to said spindle for movingsaid spindle axially between an extended bundle receiving position and aretracted position; a second stepping motor operatively connected tosaid spindle for rotating said spindle, and a programmed source ofdriving pulses for said respective stepping motors for alternatingmoving said spindle axially in stepped increments and for rotating saidspindle between said axial movement to twist said wire bundle to form aknot securing said bundle to said knot wheel plate.
 12. A machine asdefined in claim 11 including a third stepping motor for indexing saidknot wheel plate and wherein said proGrammed source of electricaldriving pulses includes means for generating groups of pulsesrepresentative of the desired angular indexing movement for said knotwheel plate to operate said third stepping motor.